learn-wgpu/code/beginner/tutorial4-buffer/challenge.rs

use winit::{
    event::*,
    event_loop::{EventLoop, ControlFlow},
    window::{Window, WindowBuilder},
};

#[repr(C)]
#[derive(Copy, Clone, Debug)]
struct Vertex {
    position: [f32; 3],
    color: [f32; 3],
}

impl Vertex {
    fn desc<'a>() -> wgpu::VertexBufferDescriptor<'a> {
        use std::mem;
        wgpu::VertexBufferDescriptor {
            stride: mem::size_of::<Vertex>() as wgpu::BufferAddress,
            step_mode: wgpu::InputStepMode::Vertex,
            attributes: &[
                wgpu::VertexAttributeDescriptor {
                    offset: 0,
                    shader_location: 0,
                    format: wgpu::VertexFormat::Float3,
                },
                wgpu::VertexAttributeDescriptor {
                    offset: mem::size_of::<[f32; 3]>() as wgpu::BufferAddress,
                    shader_location: 1,
                    format: wgpu::VertexFormat::Float3,
                },
            ]
        }
    }
}

const VERTICES: &[Vertex] = &[
    Vertex { position: [-0.0868241, -0.49240386, 0.0], color: [0.5, 0.0, 0.5] }, // A
    Vertex { position: [-0.49513406, -0.06958647, 0.0], color: [0.5, 0.0, 0.5] }, // B
    Vertex { position: [-0.21918549, 0.44939706, 0.0], color: [0.5, 0.0, 0.5] }, // C
    Vertex { position: [0.35966998, 0.3473291, 0.0], color: [0.5, 0.0, 0.5] }, // D
    Vertex { position: [0.44147372, -0.2347359, 0.0],color: [0.5, 0.0, 0.5] }, // E
];

const INDICES: &[u16] = &[
    0, 1, 4,
    1, 2, 4,
    2, 3, 4,
];

struct State {
    surface: wgpu::Surface,
    device: wgpu::Device,
    queue: wgpu::Queue,
    sc_desc: wgpu::SwapChainDescriptor,
    swap_chain: wgpu::SwapChain,

    render_pipeline: wgpu::RenderPipeline,

    vertex_buffer: wgpu::Buffer,
    index_buffer: wgpu::Buffer,
    num_indices: u32,

    challenge_vertex_buffer: wgpu::Buffer,
    challenge_index_buffer: wgpu::Buffer,
    num_challenge_indices: u32,
    use_complex: bool,

    hidpi_factor: f64,
    size: winit::dpi::LogicalSize,
}

impl State {
    fn new(window: &Window) -> Self {
        let hidpi_factor = window.hidpi_factor();
        let size = window.inner_size();
        let physical_size = size.to_physical(hidpi_factor);

        let surface = wgpu::Surface::create(window);

        let adapter = wgpu::Adapter::request(&wgpu::RequestAdapterOptions {
            ..Default::default()
        }).unwrap();

        let (device, queue) = adapter.request_device(&wgpu::DeviceDescriptor {
            extensions: wgpu::Extensions {
                anisotropic_filtering: false,
            },
            limits: Default::default(),
        });

        let sc_desc = wgpu::SwapChainDescriptor {
            usage: wgpu::TextureUsage::OUTPUT_ATTACHMENT,
            format: wgpu::TextureFormat::Bgra8UnormSrgb,
            width: physical_size.width.round() as u32,
            height: physical_size.height.round() as u32,
            present_mode: wgpu::PresentMode::Vsync,
        };
        let swap_chain = device.create_swap_chain(&surface, &sc_desc);

        let vs_src = include_str!("shader.vert");
        let fs_src = include_str!("shader.frag");
        let vs_spirv = glsl_to_spirv::compile(vs_src, glsl_to_spirv::ShaderType::Vertex).unwrap();
        let fs_spirv = glsl_to_spirv::compile(fs_src, glsl_to_spirv::ShaderType::Fragment).unwrap();
        let vs_data = wgpu::read_spirv(vs_spirv).unwrap();
        let fs_data = wgpu::read_spirv(fs_spirv).unwrap();
        let vs_module = device.create_shader_module(&vs_data);
        let fs_module = device.create_shader_module(&fs_data);

        let render_pipeline_layout = device.create_pipeline_layout(&wgpu::PipelineLayoutDescriptor {
            bind_group_layouts: &[],
        });

        let render_pipeline = device.create_render_pipeline(&wgpu::RenderPipelineDescriptor {
            layout: &render_pipeline_layout,
            vertex_stage: wgpu::ProgrammableStageDescriptor {
                module: &vs_module,
                entry_point: "main",
            },
            fragment_stage: Some(wgpu::ProgrammableStageDescriptor {
                module: &fs_module,
                entry_point: "main",
            }),
            rasterization_state: Some(wgpu::RasterizationStateDescriptor {
                front_face: wgpu::FrontFace::Ccw,
                cull_mode: wgpu::CullMode::Back,
                depth_bias: 0,
                depth_bias_slope_scale: 0.0,
                depth_bias_clamp: 0.0,
            }),
            primitive_topology: wgpu::PrimitiveTopology::TriangleList,
            color_states: &[
                wgpu::ColorStateDescriptor {
                    format: sc_desc.format,
                    color_blend: wgpu::BlendDescriptor::REPLACE,
                    alpha_blend: wgpu::BlendDescriptor::REPLACE,
                    write_mask: wgpu::ColorWrite::ALL,
                },
            ],
            depth_stencil_state: None,
            index_format: wgpu::IndexFormat::Uint16,
            vertex_buffers: &[
                Vertex::desc(),
            ],
            sample_count: 1,
            sample_mask: !0,
            alpha_to_coverage_enabled: false,
        });

        let vertex_buffer = device
            .create_buffer_mapped(VERTICES.len(), wgpu::BufferUsage::VERTEX)
            .fill_from_slice(VERTICES);
        let index_buffer = device
            .create_buffer_mapped(INDICES.len(), wgpu::BufferUsage::INDEX)
            .fill_from_slice(INDICES);
        let num_indices = INDICES.len() as u32;

        let num_vertices = 16;
        let angle = std::f32::consts::PI * 2.0 / num_vertices as f32;
        let challenge_verts = (0..num_vertices).map(|i| {
            let theta = angle * i as f32;
            Vertex {
                position: [
                    0.5 * theta.cos(),
                    0.5 * theta.sin(),
                    0.0,
                ],
                color: [
                    (1.0 + theta.cos()) / 2.0,
                    (1.0 + theta.sin()) / 2.0,
                    1.0,
                ]
            }
        }).collect::<Vec<_>>();
        
        let num_triangles = num_vertices - 2;
        let challenge_indices = (1u16..num_triangles+1).into_iter().flat_map(|i| {
            vec![i + 1, i, 0]
        }).collect::<Vec<_>>();
        let num_challenge_indices = challenge_indices.len() as u32;

        let challenge_vertex_buffer = device
            .create_buffer_mapped(challenge_verts.len(), wgpu::BufferUsage::VERTEX)
            .fill_from_slice(&challenge_verts);
        let challenge_index_buffer = device
            .create_buffer_mapped(challenge_indices.len(), wgpu::BufferUsage::INDEX)
            .fill_from_slice(&challenge_indices);

        let use_complex = false;

        Self {
            surface,
            device,
            queue,
            sc_desc,
            swap_chain,
            render_pipeline,
            vertex_buffer,
            index_buffer,
            num_indices,
            challenge_vertex_buffer,
            challenge_index_buffer,
            num_challenge_indices,
            use_complex,
            hidpi_factor,
            size,
        }
    }

    fn update_hidpi_and_resize(&mut self, new_hidpi_factor: f64) {
        self.hidpi_factor = new_hidpi_factor;
        self.resize(self.size);
    }

    fn resize(&mut self, new_size: winit::dpi::LogicalSize) {
        let physical_size = new_size.to_physical(self.hidpi_factor);
        self.size = new_size;
        self.sc_desc.width = physical_size.width.round() as u32;
        self.sc_desc.height = physical_size.height.round() as u32;
        self.swap_chain = self.device.create_swap_chain(&self.surface, &self.sc_desc);
    }

    fn input(&mut self, event: &WindowEvent) -> bool {
        match event {
            WindowEvent::KeyboardInput {
                input: KeyboardInput {
                    state,
                    virtual_keycode: Some(VirtualKeyCode::Space),
                    ..
                },
                ..
            } => {
                self.use_complex = *state == ElementState::Pressed;
                true
            }
            _ => false,
        }
    }

    fn update(&mut self) {

    }

    fn render(&mut self) {
        let frame = self.swap_chain.get_next_texture();

        let mut encoder = self.device.create_command_encoder(&wgpu::CommandEncoderDescriptor {
            todo: 0,
        });

        {
            let mut render_pass = encoder.begin_render_pass(&wgpu::RenderPassDescriptor {
                color_attachments: &[
                    wgpu::RenderPassColorAttachmentDescriptor {
                        attachment: &frame.view,
                        resolve_target: None,
                        load_op: wgpu::LoadOp::Clear,
                        store_op: wgpu::StoreOp::Store,
                        clear_color: wgpu::Color {
                            r: 0.1,
                            g: 0.2,
                            b: 0.3,
                            a: 1.0,
                        },
                    }
                ],
                depth_stencil_attachment: None,
            });

            render_pass.set_pipeline(&self.render_pipeline);

            let data = if self.use_complex {
                (
                    &self.challenge_vertex_buffer, 
                    &self.challenge_index_buffer, 
                    self.num_challenge_indices
                )
            } else {
                (
                    &self.vertex_buffer,
                    &self.index_buffer,
                    self.num_indices,
                )
            };
            render_pass.set_vertex_buffers(0, &[(data.0, 0)]);
            render_pass.set_index_buffer(data.1, 0);

            render_pass.draw_indexed(0..data.2, 0, 0..1);
        }

        self.queue.submit(&[
            encoder.finish()
        ]);
    }
}

fn main() {
    let event_loop = EventLoop::new();
    let window = WindowBuilder::new()
        .build(&event_loop)
        .unwrap();

    let mut state = State::new(&window);
    
    event_loop.run(move |event, _, control_flow| {
        match event {
            Event::WindowEvent {
                ref event,
                window_id,
            } if window_id == window.id() => if state.input(event) {
                *control_flow = ControlFlow::Wait;
            } else { 
                match event {
                    WindowEvent::CloseRequested => *control_flow = ControlFlow::Exit,
                    WindowEvent::KeyboardInput {
                        input,
                        ..
                    } => {
                        match input {
                            KeyboardInput {
                                state: ElementState::Pressed,
                                virtual_keycode: Some(VirtualKeyCode::Escape),
                                ..
                            } => *control_flow = ControlFlow::Exit,
                            _ => *control_flow = ControlFlow::Wait,
                        }
                    }
                    WindowEvent::Resized(logical_size) => {
                        state.resize(*logical_size);
                        *control_flow = ControlFlow::Wait;
                    }
                    WindowEvent::HiDpiFactorChanged(new_hidpi_factor) => {
                        state.update_hidpi_and_resize(*new_hidpi_factor);
                        *control_flow = ControlFlow::Wait;
                    }
                    _ => *control_flow = ControlFlow::Wait,
                }
            }
            Event::EventsCleared => {
                state.update();
                state.render();
                *control_flow = ControlFlow::Wait;
            }
            _ => *control_flow = ControlFlow::Wait,
        }
    });
}